The detail of how the car was prepaired is here:
http://www.tulsahistory.org/events/buriedcar.htm
"A huge plastic bag made by Kennedy Car Liners was positioned over the car with the bottom edges heat sealed to the base sheet, leaving a 4-inch slot opening. The air in the bag was then vacuumed out through the slot producing a hermetically-sealed container."
So the question is if the seals on the bag held or not? The weight of the water pressing against the bag due to the vault leak is the biggest potential source of the seam failure or puncture failure. The bag does look still collapsed in the inital Photos.
